Capacity models of rc members with emphasis on sub-standard columns with plain bars

Current code prescriptions allow to evaluate the ultimate rotational capacity from hybrid (mechanical-empirical) or empirical formulations, for R.C. members with deformed bars and seismically detailed. These formulations can be extended to non-conforming elements by applying correction coefficients calibrated on experimental data. These coefficients, for members with plain bars, imply a reduction of 40% at least; this reduction increases if lapping of longitudinal bars is present. The experimental campaign conducted at the University of Naples on 16 real-scale columns with plain bars allowed to extend the experimental database for this typology. Experimental results highlight the excessive conservativeness of the current code proposal. Based on these results, new correction coefficients are proposed.